Willie, if you want to stay under £400 and want to buy a new set the only ones I would recommend would be a set of Golfsmith Pro Forged Blades, which could be custom fit. Although you may not have heard of Golfsmith (they are a component company) these are a very good set of double forged blades. A cutsom set of these could be made up for around £390. On the other hand if you would consider second hand then you could chose from quite a range for about the same figure. Check out Golfbidder.com for examples.
If you are wanting to switch to blades, and I wouldn't recommend it to everyone as they are a much more demanding club to play with, then most of the leading manufacturers are of good quality. Personally I play with Mizuno MP-14's which I love, but the new MP-33's are the one to go for if you can find them in your price range. Another couple to consider are Cleveland TA-1, and Hogen Apex (or Apex Plus) which are all quality clubs and definately worth a demo.
If you are making a set up to forged irons, don't over look the slightly more forgiving cavity back ones (Cleveland TA3, Apex Plus, Mizuno Pro II or MX-20). The best advice I could offer though is to make sure that you get the right shafts and have the lies and lengths altered to suit you - or the quality of the heads will make no difference.
Best of Luck.
